Current systems for loading large cargo loads onto the bed of a light truck, such as a pickup truck, are cumbersome and, occasionally, unsafe. Such a load might include a slip-in camper, a heavy piece of equipment, a light-duty vehicle, or, otherwise, a cargo box of out-sized dimension. The cargo load is characterized by size or weight too large to be conveniently handled unaided by one person.
Existing systems use jacks, or hydraulic cylinders, to lift the load off the ground while the vehicle is driven underneath. Such systems are expensive, a nuisance to install or remove, and they take up space on the bed which could otherwise be used for cargo. More importantly, however, there is a risk of a calamitous result.
The driver of the truck has to navigate through the scaffolding suspending the load with limited vision to the rear. The view of the bed or inner fenders from the driver's seat of an extended cab, or crew cab, on a pickup truck, for example, is limited. A collision with the jacks holding up a camper, as an example, could cause the camper to catastrophically collapse.
Means for rigging the load by using a ramp, and thereby avoiding the risk inherent in suspending the load, are known. U.S. Pat. No. 6,099,232 to Dixon, for example, discloses a system for loading a small recreational vehicle, such as a motorcycle, onto a light truck. The system involves an installation of rails on the truck bed, a pallet to move laterally on the rails and pivotally at the distal end thereof to provide a ramp, and a carriage to contain the load and move it onto the sled. Loading is accomplished by two winches manipulating the carriage onto the pallet and tipping the pallet onto the rails. Lateral movement on the bed, however, requires a manual effort to shove the load forward or rearward.
The rails and pallet of Dixon, while facilitating the lateral movement of the cargo, otherwise render the truck bed unusable for other purposes. The installed structure could be eliminated by using a winch, or another power means, to tow the load over the bed. A single winch acting alone is insufficient, however, because it can only force in one direction; that is to say, it can either load or unload.
A pair of winches positioned oppositely along the path of movement can alternately pull in one direction to load or pull in the other direction to unload. While the winches could be selectively engaged by operator control, the challenge is to configure a system where the winches act cooperatively in opposition. The resulting counterbalance provides a braking force to slow the driving winch and control the gravity decent down the ramp. This cooperative action is complicated by the dynamic of the unloading cycle. While moving laterally, friction acts against the pulling winch. During the ramp descent phase, however, gravity acts to precipitately reinforce the pull. The two winches seemingly have the need to communicate with each other.
It is known that microprocessor-based controls can be provided and programmed for automated speed control between opposing winches. Hydraulic winches, in particular, are adaptable to speed control by shunting fluid. Hydraulic winches and sophisticated control mechanisms, however, are too expensive and complex for the ordinary homeowner, or sportsman, experiencing the casual need to boost a heavy load onto a pickup truck.
The instant invention provides the means by which two relatively inexpensive and commonly-available winches can act in opposition while adjusting themselves automatically to balance the net force on the load. The novel approach is distinguished by the absence of a coordinating control mechanism. In another embodiment, a single winch combined with a deadhead anchor and a simple mechanism to maintain winch cable tension is presented.